Quote from RickAJr >>

DC15 (medium): does not have any damage resistances nor damage vulnerabilities DC20 (hard): immune to damage from cold attack

 Don't these two contradict, just a little?

Resistances and Vulnerabilities are not the same thing as Immune.

In game mechanic terms, yeah, but it seems like a weird distinction to make to me anyway.

it is a bit odd to lead with a description to "provide better immersion" then have a list of information expressed as game mechanics. In role-playing terms being immune to something is being totally resistant to it. It doesn't take prior knowledge for the CHARACTERS to know a creature with sharp teeth is going to bite. 

The large creature before you has a beaked nose, spiny dewlaps, and a crest supported by a single, back-curving spine, where its wings cast no shadow its scaled body glistens like snow. freezing cold breath pours between its menacing teeth and lingers as a fog around its claws. 

Wisdom (Perception) DC10: There is a crisp, faintly chemical odor. 

Intelligence (Arcana/History/Nature) DC5- Its a white dragon, DC10- it can freeze you with its breath and cold cannot harm it, DC15- this is a young one, DC20- it can see in the dark

It doesn't take prior knowledge for the CHARACTERS to know a creature with sharp teeth is going to bite. 

It would be the equivilant to a failed role without saying "you failed your role" haha

Can someone please help explain why the attribute modifiers are different than the modifiers for the attribute saves? Thanks.

It's proficient in those saving throws with a proficiency bonus of +3

Thanks. Is it safe to assume that one takes the higher modifier only? For example for Constitution, it would be a +7 not a +4 (or +11). I assume the attribute modifiers are "already in" the Saving Throw proficiency modifiers.

As Bendas already explained: It has a +3 proficiency bonus. It is proficient in those four saves. Those four saves include +3 from the proficiency bonus and the appropriate stat bonus. There is no assumption involved here. If the dragon has to make one of those four saves that it is proficient in, use that bonus. For STR and INT saves (which it is not proficient) only use the ability check. 

Don't assume, do the math yourself to check:

Dex +0. Dex Save +3. 3+0=3. Con +4. Con Save +7. 3+4=7. And so on. Those four saves are all exactly 3 higher than the ability. 

I have this question as well, running icespire hold and party getting close to heading towards cryovain.
Also what’s the height and wingspan of a young white dragon/cryovain? 

refer to this and do +/-10% ?

https://www.dndbeyond.com/sources/basic-rules/combat#CreatureSize

I’m running DoIP and we just did dragon barrow and circle of thunder (at level 5), defeated gorthok, then the dragon got rolled and was encountered as we were going back to phandalin, it got initiative 3, then the cavalier has mounted combatant (adv. on melee attacks from horse, some other things) and crit with the dragon slayer and warlock got 43 damage from a 3rd lv fireball then we killed the dragon

What happens if the dragon is killed when on a random encounter?

It's entirely up to you. Personally I would have tried getting the dragon to flee, even lying about his remaining health as long as the damage wasn't massive overkill. But seems like that ship has sailed.

Otherwise you can introduce a second dragon as it's mate, parent or rival. Was there much dialogue? Would the player's know that was definitely the only white dragon they've seen flying around? Maybe there were 2 and this one was kicked out of icespire by an even bigger/stronger dragon.

There was a green dragon in thundertree (lost mine of Phandelver) that you could work in as the new bad guy. 

Or just start the next campaign, they killed the dragon.

Quote from Dudhhr >>

I’m running DoIP and we just did dragon barrow and circle of thunder (at level 5), defeated gorthok, then the dragon got rolled and was encountered as we were going back to phandalin, it got initiative 3, then the cavalier has mounted combatant (adv. on melee attacks from horse, some other things) and crit with the dragon slayer and warlock got 43 damage from a 3rd lv fireball then we killed the dragon

What happens if the dragon is killed when on a random encounter?

 Kind of dealing with this myself. Party had a random encounter with the dragon at Conyberry. Thought it would show up killing an animal, they would freak out then it would leave. Iwas mostly right as the majority decided to hide. But one chose to taunt the dragon. So I thought a quick chase with a cold breath would scare them. It kind of worked but the next two rounds of combat the party (level 4) joined in and wrecked the Dragon. Good thing I maxed the hp or it would have died.

one thing I decided to do is that dragon is not fighting them again, remembering the threat they were, except when in its lair as the lair actions will help empower the dragon. May also add some really low level mobs so the action economy doesn’t overwhelm the dragon. I am also considering adding another threat, a force that is controlling the dragon.

Just finished dragon of icespire peak campaign!!! We probably would have died if we didnt have three dragonborns in the campaign!!

i'm starting one it

I'm a player in Dragon of Icespire Peak, and next session or the one after we're going to be fighting the young white dragon.

ResnepsNrobnogard - May your blade be sharp, your arrows strike true, and your great balls of fire bring the burn!

Another player shot it with an arrow with a Bead of Fireball (and I think got a critical hit), and I then Fireballed it myself (I'm a wizard) before our Paladin killed it with a dragon slayer longsword and Divine Smite. First dragon I've fought.